System and method for scaphoid fixation

ABSTRACT

A system and method for installation of a k-wire through a scaphoid or other fractured bone can include a guide block for accurate trajectory of a k-wire. A support frame for a guide block can be casted and/or secured into place, and a CT scan is obtained, so the fractured bone and the location of the window can be known in the same three-dimensional space. An ideal k-wire trajectory can be plotted through the fractured bone, and a guide block with a lumen can be designed and printed using a three-dimensional printer. The guide block can be inserted into the frame so the lumen aligns with the ideal k-wire trajectory, and a k-wire can be inserted through the lumen into the fractured bone. The net effect would be ideal placement of the k-wire that would facilitate the ultimate insertion of a percutaneous screw to provide fixation of the fractured bone.

RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser.No. 62/525,158, entitled SYSTEM AND METHOD FOR SCAPHOID FIXATION, filedJun. 26, 2017, the teachings of which application are expresslyincorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to percutaneous fixation of a fractured bone, andmore particularly to a guide that allows for accurate placement of ak-wire, which provides the guide for placement of a cannulated screwthat provides final fixation of the fracture

BACKGROUND OF THE INVENTION

Scaphoid fractures are among the most common fractures of the wrist.These fractures are often repaired by installing a percutaneous screwinto the fractured bone. Correct placement of the percutaneous screw canbe difficult, and sometimes can require multiple attempts at K-wireplacement. Screw placement can be aided by a guide wire, known as aK-wire, which can be installed through the bone, and later removed afterthe screw has been placed. Doctors commonly use intraoperativefluoroscopy to help ensure correct placement of the K-wire and/orpercutaneous screw. Current surgical techniques for treatment consist ofplacing a K-wire percutaneously and then inserting a cannulated screwover the K-wire. Placement of the K-wire can be difficult given thecomplex structure of the scaphoid bone, thereby causing increasesurgical time, radiation exposure, and cost. It would be desirable to beable to install a K-wire and/or percutaneous screw in a single attemptthereby resulting in decreased surgical time and expense. It wouldfurther be desirable to correctly install the K-wire and/or percutaneousscrew without exposing the patient and medical staff to repeated roundsof radiation from the fluoroscopic imaging that can occur throughmultiple attempts at K-wire placement. By decreasing the surgical timeand increasing the efficiency of the procedure, an economic benefitwould be seen by hospitals and payers of health care.

SUMMARY OF THE INVENTION

The present invention overcomes the disadvantages of the prior art byproviding a system and method for designing a K-wire guide that can becustomized to each patient. The present invention further provides asystem and method for using the K-wire guide to correctly install aK-wire in a scaphoid bone in one attempt, without the need forreiterative placement, imaging, and placement adjustments. This systemand method that ensures accurate placement can overcome disadvantages inthe prior art by avoiding weakening the damaged bone with multipleholes, decreasing surgery time, reducing radiation exposure fromfluoroscopic imaging, reducing the opportunity for surgeon error, andincreasing efficacy of surgery, among other benefits.

In an embodiment, a system for installing a k-wire can include a guideblock with a central lumen through the guide block, so that the centrallumen is along a predetermined k-wire trajectory. The system can alsoinclude a support frame having at least one sidewall configured forholding the guide block. The support frame can be adapted to be heldsecurely relative to a fractured bone of a patient, and the guide blockcan be designed to fit within the support frame, so that the centrallumen of the guide block is aligned along the predetermined k-wiretrajectory.

The system can include a cast, with the support frame adapted to be heldin place relative to the patient's fractured bone by the cast. Thesupport frame can include a brim. The at least one sidewall can define ablock chamber that defines a first area near the brim that is smallerthan a second area distant from the brim. The system can include a guidesleeve having a central lumen that is aligned along the predeterminedk-wire trajectory. The guide block can include a frustum. The k-wiretrajectory can define a predetermined path through the fractured bone.

In an embodiment, a method for installing a k-wire can include securinga support frame for a guide block relative to a fractured bone of apatient, obtaining a three-dimensional CT scan of the fractured bone andthe support frame, with the scan containing the fractured bone and thesupport frame in the same three-dimensional space, plotting a trajectoryfor a k-wire through the fractured bone, with the trajectory in the samethree-dimensional space, identifying the location of the support framerelative to the fractured bone and the trajectory in thethree-dimensional space, designing a k-wire brace with a central lumen,so that the k-wire brace is designed to fit within the support frame,and so that the k-wire brace is aligned along the trajectory when theguide block is inserted within the support frame, preparing the k-wirebrace, and securing the k-wire brace within the support frame

The method can include installing a k-wire through the central lumen ofthe k-wire brace and through the fractured bone. The method can includeinstalling a cannulated screw along the k-wire. Preparing a k-wire bracecan include printing a guide block using a three-dimensional printer.Preparing a k-wire brace can include adjusting a stereotaxic instrument.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention description below refers to the accompanying drawings, ofwhich:

FIG. 1A is a perspective view of a k-wire guidance system with a guideblock, according to an embodiment;

FIG. 1B is a perspective view of a k-wire guidance system with astereotaxic instrument, according to an embodiment;

FIG. 2 is a perspective view of a support frame for a k-wire guideblock, according to an embodiment;

FIG. 3 is a perspective view of a support frame showing placement of theframe relative to a patient's wrist, according to an embodiment;

FIG. 4 is a perspective view of a cast holding a support frame in placeon a patient's wrist, according to an embodiment;

FIG. 5 shows a 3-dimensional reconstruction from a CT of a patient'swrist with a window casted in place on the wrist, according to anembodiment;

FIG. 6 shows a 3-dimensional reconstruction from a CT of a scaphoid bonewith two points that define a trajectory for a k-wire through thescaphoid bone, according to an embodiment;

FIG. 7 shows a reconstruction from a CT of a skeleton showing atrajectory for a k-wire through a scaphoid bone, according to anembodiment;

FIG. 8 shows a reconstruction from a CT of a frame fixed in a cast andshowing reference points on the frame to be used in creating a3-dimensional model of a guide block, according to an embodiment;

FIG. 9 shows a side view of a 3-dimensional model of a guide block and ascaphoid bone with a k-wire trajectory passing through the scaphoid boneand the guide block, according to an embodiment;

FIG. 10 shows a top view of a 3-dimensional model of a guide block and askeleton with a k-wire trajectory passing through the scaphoid bone andthe guide block, according to an embodiment;

FIG. 11 shows a perspective view of a guide block with a guide sleeve;

-   -   according to an embodiment;

FIG. 12A shows a bottom view of a guide block with a guide sleeve,according to an embodiment;

FIG. 12B shows a bottom view of a guide block with a k-wire lumen,according to an embodiment;

FIG. 13 shows a perspective view of a guide block held within a supportframe, according to an embodiment;

FIG. 14 shows a perspective view of a patient's wrist with a windowcasted in place, and a support block with a sleeve, according to anembodiment;

FIG. 15 shows a perspective view of a patient's wrist with a windowcasted in place, and a support block with a sleeve held in place withinthe window, according to an embodiment;

FIG. 16 shows a perspective view of a k-wire being inserted through aguide sleeve and into the scaphoid bone, according to an embodiment;

FIG. 17 shows a perspective view of a patent's casted wrist with aninserted k-wire extending through the guide block and guide sleeve,according to an embodiment;

FIG. 18 shows a perspective view of a patient's casted wrist with theguide block removed and with an inserted k-wire extending from the palm,according to an embodiment;

FIG. 19 shows a perspective view from a CT showing a k-wire that hasbeen properly installed through a scaphoid bone;

FIG. 20 shows a different perspective view from a CT showing a k-wirethat has been properly installed through a scaphoid bone; and

FIG. 21 shows a perspective view of a patient's casted wrist with aninserted k-wire that has been cut for use as a guide for a percutaneousscrew, according to an embodiment.

DETAILED DESCRIPTION

FIG. 1A is a perspective view of a k-wire guidance system with a guideblock, according to an embodiment. In the illustrative embodiment, ak-wire guidance system 100 can include a cast 102, a guide frame 104,and a k-wire brace that can be a guide block 106. The cast 102 can be acommon plaster cast, or other casting system as is known in the art forallowing bones to heal, or the cast can be another device to allowfixation of the guide frame to the arm. The cast can immobilize thewrist of a patient from the elbow to the fingers. The K-wire targetingdevice is secured in place relative to the fractured bone, and mayconsist of a cast or other device in order to secure it. A frame 104 canbe placed against a patient's hand and/or wrist, and casting materialcan be wrapped around the patient's hand and lower arm, thereby securingthe frame 104 in a fixed position against the patient's hand and/orwrist. A guide block 106 can be inserted into the frame 104, so that theguide block 106 is held in a fixed position relative to the patient'shand and/or wrist, so that the guide block 106 can also be in a fixedposition relative to the bones in the patient's hand and wrist. Theguide block 106 can have a guide sleeve 108. The guide sleeve 108 canhave a k-wire lumen 110 that is sized to accommodate a k-wire, so thatthe k-wire can be inserted into the k-wire lumen 110 of the guide sleeve108. The guide block 106 can maintain the k-wire in a fixed trajectoryrelative to the bones in the patient's hand and wrist. The k-wire can beinserted through the guide block 106, and can be further inserted into abone of the patient, e.g. a scaphoid bone.

FIG. 1B is a perspective view of a stereotaxic instrument for a k-wireguidance system, according to an embodiment. In various embodiments ak-wire brace can be a stereotaxic instrument 120 that can be insertedinto the guide frame 104 and held in a fixed position and orientationrelative to a bone of the patient. The stereotaxic instrument 120 can beused to guide a k-wire along a predetermined trajectory through ascaphoid or other bone of the patient. The stereotaxic instrument 120can have an adjustably positionable guide sleeve 122 that can beadjustably positioned through four or more degrees of freedom to bepositioned along the desired trajectory.

In various embodiments, a guide sleeve 122 can move through a firstdegree of freedom along arrows DF1 by sliding along a first support 124.Guide sleeve 122 can slide within a channel in first support 124, or canhave an extension that slidably engages with first support 124, or othermeans that will be obvious to one skilled in the art. Guide sleeve 122can move through a second degree of freedom along arrows DF2 by pivotingthe first support 124 relative to one or more second supports 126. Guidesleeve 122 can move through a third degree of freedom along arrows DF3by sliding the one or more second supports 126 along one or more thirdsupports 128. Guide sleeve 122 can move through a fourth degree offreedom DF4 by sliding the one or more second supports along one or morefourth supports 130. The stereotaxic instrument can have a centralopening 132 that allows the guide sleeve and k-wire to pass through thecentral opening so that a surgeon can direct a k-wire through thestereotaxic instrument and into a scaphoid or other bone. Thestereotaxic instrument can have a frustum portion 134 that can be sizedand shaped to be held securely within the guide frame 104. In variousembodiments, a stereotaxic instrument can have a wide variety ofdifferent types and arrangements of supports, pivots, sliders, hinges,or other components of a stereotaxic instrument that will be obvious toone skilled in the art.

A stereotaxic instrument 120 can have graduated markings along eachdegree of freedom, and can have clamps or other means for selectivelyallowing or prohibiting movement along each degree of freedom. A surgeoncan use the graduated markings to guide the adjustment of the guidesleeve through multiple degrees of freedom into a predetermined positionthat can be along the desired k-wire trajectory. The stereotaxicinstrument can be held in the guide frame in a known position relativeto the bone of the patient, so that the guide sleeve 122 can be fixedsecurely along the desired trajectory relative to the scaphoid. Thek-wire can then be inserted through the guide sleeve and into a bone ofthe patient.

FIG. 2 is a perspective view of a support frame for a k-wire guideblock, according to an embodiment. In the illustrative embodiment, asupport frame 104 can have a window 202, a brim 204, a waist 206, and ablock holder 210. A support frame 104 for a k-wire guide block can bedesigned to be placed against the hand and/or wrist of a patient, andcan be casted in place so that it can be held firmly in place relativeto bones in the hand and/or wrist of the patient. The brim 204 can beshaped to rest securely against the hand and/or wrist of the patient. Inan embodiment, the brim 204 can be convex. Casting material can overlaythe brim 204, so that the casting material can hold the support frame104 in place against the hand and/or wrist of the patient, and thecasting material can prevent the support frame from being pulled out ofthe cast or moved relative to bones of the patient.

The support frame 104 can have a block holder 210 that extends above thebrim 204. The block holder 210 can have at least one sidewall 212 thatcan hold a guide block 106 securely in place. A sidewall 212 can have aninner sidewall surface 214 and an outer sidewall surface 216. In anillustrative embodiment, the block holder 210 can define a quadrilateralwindow, and the block holder 210 can have four inner sidewall surfaces214, but in alternate embodiments, the block holder 210 can define anoval-shaped window with a single sidewall, a triangular window withthree sidewalls, or other various numbers or arrangements of sidewallsforming a window. In an embodiment, the window can be asymmetric, sothat the guide block cannot be inserted incorrectly. In variousembodiments, the frame can be free of sidewalls extending upwards fromthe brim. The frame can have a window that is free of surroundingsidewalls extending upwards, and the guide block can be inserted intothe window of the frame without the need for upwardly-extendingsidewalls to contact the guide block, and the guide block can be held inplace through contact with the edges of the window. The frame can be aplate with a rectangular, triangular, or other appropriate window shapecut into the plate. The frame can have anchoring points on the framethat can be used to secure the guide block in the correct location, sothat the guide block does not need to be held in place by sidewalls orthe edges of the window.

In the illustrative embodiment of FIG. 2, the inner sidewall surfaces214 can be angled upwards and outwards to accommodate a frustum-shapedportion of a guide block. The block holder 210 can define a blockchamber that can be a space within the block holder adapted to hold aguide block. The block chamber can be frustum-shaped surrounding asmaller area near the brim and a larger area distant from the brim. Theblock holder 210 can have multiple reference points 218. The referencepoints 218 can be corners and/or edges of the block holder 210. Invarious embodiments, the reference points can be small stubs extendingfrom the frame in known locations, embedded objects like pieces of steelin known locations that can easily be identifiable in CT, depressions inthe frame in known locations, or other means for identifying referencepoints that will be obvious to those skilled in the art. In theillustrative embodiment, there can be eight reference points 218 thatcan be the top corners and bottom corners where each inner sidewallsurface 214 meets other inner sidewall surfaces 214. The support framecan have a waist 206 where the outer sidewall surface 216 of the blockholder 210 meets the top surface of the brim 206. Casting material, orother material used to hold the support frame in place, can abut thewaist 206 and/or outer sidewall surfaces 216, so that the support frame104 can be held securely by the cast in a fixed location relative tobones of the patient.

FIG. 3 is a perspective view of a support frame showing placement of theframe relative to a patient's wrist, according to an embodiment. A spot302 can be marked on a patient's skin demonstrating the location of thescaphoid tubercle as an anatomic reference point. The patient's hand canbe positioned with the fingers pointing up and the elbow pointing down,and the support frame can be positioned against the hand and/or wrist sothat the brim 204 is adjacent to the patient's hand and/or wrist. Thesupport frame can be positioned so that the spot 302 showing thescaphoid tubercle can be approximately near the central long axis 304 ofthe window 202, and the spot 302 can be approximately in the bottomthird of the window 202. In various alternate embodiments, the supportframe 104 can be designed to assist in repairing other fractured bones,and the window of the support frame can be positioned accordinglyrelative to a fractured bone to be repaired.

FIG. 4 is a perspective view of a cast holding a support frame in placeon a patient's wrist, according to an embodiment. Casting material canbe used to form a cast 102 that can hold the support frame 104 securelyin place relative to the fractured bone. In the illustrative embodiment,the cast can immobilize the hand, wrist, and arm from the fingers to theelbow, and can hold the frame securely in place against the hand and/orwrist. The casting material can overlay the brim and can abut the waistand/or sidewalls 212 to hold the support frame 104 in a fixed positionrelative to the fractured bone.

FIG. 5 shows a 3-dimensional reconstruction from a CT of a patient'swrist with a window casted in place on the wrist, according to anembodiment. After the window is embedded in the cast in an appropriateposition and orientation, the patient's wrist can be scanned using a CT.The wrist can be scanned at a high resolution that can be, for example,approximately 0.6 mm or smaller depending on CT capabilities. A3-dimensional reconstruction 500 of the patient's wrist can be createdfrom the CT scan. As shown in FIG. 5, bones of the patient, includingthe scaphoid bone 502, can be seen in the 3-dimensional reconstruction.The cast 102 with the window 202 can also be seen in the 3-dimensionalreconstruction. This 3-dimensional reconstruction 500 can provide datathat can be used to create the guide block 106 for the k-wire.

A 3-dimensional reconstruction of the skeleton from a CT can besegmented to isolate a fracture. This can allow a surgeon or othermedical provider to visualize the fracture. The segmentation of theskeleton can be done using a computer to highlight the fractured bone.The segmentation of the skeleton can be used to identify where aparticular bone, such as the scaphoid, is located in a known threedimensional space.

The procedure can be based on thresholding of the bone while keepingother features out, such as the cast and window. Thresholding canisolate pixels or voxels that have values greater than a specifiedthreshold. In x-ray CT, bone has higher attenuation and can usually beseen as very light (whiter) than the surroundings. By isolating bonepixels or voxels, it is possible to maintain a 3-dimensional view of theskeleton. Following thresholding it can be possible to remove from thevisible set of pixels or voxels the pixels or voxels that are not partof the scaphoid to isolate the scaphoid and allow a medical provider tovisualize the scaphoid alone in 3-dimensions. This can create a usablerepresentation of the scaphoid in 3 dimensions, that can be either as avoxel volume or as a surface defined by nodes and facets, as will beunderstood by one skilled in the art.

FIG. 6 shows a 3-dimensional reconstruction from a CT of a fracturedscaphoid bone, with two points that define a trajectory for a k-wirethrough the scaphoid bone, according to an embodiment. As shown in theexemplary embodiment of FIG. 6, the skeleton has been segmented toisolate the scaphoid bone 502, which can be visualized in 3 dimensions.An entry point 602 and an exit point 604 can be identified on the bone.The entry point 602 and exit point 604 can define a trajectory for thek-wire. It should be clear that the insertion of the k-wire could beperformed from either side of the wrist, and the k-wire could enter orexit through either of the entry point 602 and exit point 604. For thesake of clarity, the method defined herein describes insertion of thek-wire through the palm and entering the scaphoid through entry point602, however an opposite trajectory entering through exit point 604 andexiting through entry point 602 is specifically contemplated.

FIG. 7 shows a reconstruction from a CT of a skeleton showing atrajectory for a k-wire through a scaphoid bone, according to anembodiment. The entry point 602 and exit point 604 define a trajectoryline 702. Trajectory line 702 shows an intended trajectory for a k-wirethrough a scaphoid bone. The trajectory line 702 can be placed in thecentral ⅓ axis of the scaphoid without breaching the cortical bone, aswould be obvious to a surgeon or radiologist skilled in k-wireplacement.

FIG. 8 shows a reconstruction from a CT of a frame fixed in a cast andshowing reference points on the frame to be used in creating a3-dimensional model of a guide block, according to an embodiment. The3-dimensional CT of the cast 102, the support frame 104, and the partialskeleton, as shown in FIG. 5 can be segmented to isolate the cast 102and the support frame 104. Because the material of the support frame canbe less dense than bone, a lower thresholding value can be used toisolate the support frame. The support frame 104 can be isolated toobtain a 3-dimensional representation of the frame 104, including theblock holder 210. Isolating the frame 104 can allow a guide block 106 tobe designed to fit within the frame 104. The reference points 218 of thesupport frame can be identified in the 3-dimensional reconstruction ofthe CT. Identifying the location of the eight reference points 218 inthe 3-dimensional space allows the locations of the four section planes,or inner sidewall surfaces 214, to be known. In alternate embodiments, awindow with a different shape is possible, and identification ofreference points can allow the locations of the at least one innersidewall surface to be known.

The four inner sidewall surfaces 214 in the present embodiment canrepresent a section of a frustum. After the locations of the innersidewall surfaces 214 have been identified in the 3-dimensional spacethrough identification of the reference points 218, a section of afrustum can be identified in the 3-dimensional space through theidentification of the inner sidewall surfaces 214. The frustum definedby the inner sidewall surfaces 214 can form the basis for designing theguide block 106.

FIG. 9 shows a side view of a 3-dimensional model of a guide block and ascaphoid bone with a k-wire trajectory passing through the scaphoid boneand the guide block, according to an embodiment. Because the location ofthe scaphoid bone 502, the location of the intended k-wire trajectory702, and the location of the frustum defined by the inner sidewallsurfaces are all known in the same 3-dimensional space, a 3-dimensionalmodel of a guide block 902 can be designed to fit securely in the windowwith the intended k-wire trajectory 702 passing through the3-dimensional model of the guide block 902. The thickness of the modelof the guide block 902 can be designed so that it does not extend belowthe sidewall inner surfaces 214 and/or does not occupy the same space asthe patient's hand and/or wrist. The thickness of the model of the guideblock 902 can extend as far out from the patient as desired to ensureadequate guidance of the k-wire.

FIG. 10 shows a top view of a 3-dimensional model of a guide block and askeleton with a k-wire trajectory passing through the scaphoid bone andthe guide block, according to an embodiment. The three dimensionalrepresentation of the guide block 902 is shown with a guide sleevecavity 1002. The guide sleeve cavity 1002 can be designed so that aguide sleeve with a k-wire lumen can be inserted into the guide sleevecavity 1002 in the guide block. In embodiments without a guide sleeve, ak-wire lumen can pass entirely through the guide block. The3-dimensional representation of a guide block 902 can be designed with aguide sleeve cavity 1002 so that the intended k-wire trajectory 702passes through the guide sleeve cavity 1002. This three dimensionalmodel of a guide block 902 can then be used to create a physical guideblock 106. The physical guide block, which is based on the 3-dimensionalmodel 902, can be designed to be sized and shaped to fit securely andprecisely within the window of the frame, and the guide sleeve cavity1002 can be sized and shaped for the guide sleeve to fit securely andprecisely within the guide sleeve cavity 1002. The guide block can alsobe designed, based on the model 902, with the intended k-wire trajectorypassing through a k-wire lumen in the guide block, so that k-wire lumencan be used to guide the k-wire along the desired trajectory through thescaphoid bone. In various embodiments, the guide block can have a guidesleeve cavity 1002 extending all the way through the guide block, sothat a guide sleeve can be inserted all the way through the guide block,and the k-wire lumen can pass through the guide sleeve, or the guideblock can be free of a guide sleeve and can have the k-wire lumenextending all the way through the guide block, so that the k-wiretrajectory can pass through the k-wire lumen. In an embodiment, theguide sleeve cavity can extend from the top of the guide block andpartially through the guide block with the bottom of the guide sleevecavity at a known depth in the guide block, and a k-wire lumen canextend through the guide sleeve, and from the bottom of the guide sleevecavity to the bottom of the guide block, so that the k-wire trajectorycan pass through the guide sleeve and through the guide block.

FIG. 11 shows a perspective view of a guide block with a guide sleeve;according to an embodiment. A guide block 106 can be printed by a3-dimensional printer based on the 3-dimensional model 902. The guideblock 106 can have outer block walls 1102 that can define a frustumportion 1104 of the guide block 106. The frustum portion 1104 can bewider at the top and narrower near the patient. The frustum portionshown in FIG. 11 is depicted with planar sides, however, it should beclear that the sides can be curved, or stepped, or have other shapesthat are wider at the top and narrower at the bottom, so that they canbe held securely by the support frame in a known orientation. The topand/or bottom of the frustum portion can be planar, or can be curved orother non-planar shapes. The frustum portion 1104 is sized and shaped tobe held securely within the window of the guide frame. The guide blockcan have a top surface 1106, and the top surface 1106 can include aguide sleeve 108. The guide sleeve 108 can have a k-wire lumen 110 sizedand shaped to accommodate a k-wire. In the embodiment shown in FIG. 11,the guide block 106 can be printed with a guide sleeve cavity extendingfrom the top surface 1106 through at least a portion of the guide block106. The guide sleeve cavity can be designed for a guide sleeve 108 tobe inserted into the guide sleeve cavity. The guide sleeve cavity can bea cylindrical hole, square hole, or other hole designed to accommodate aguide sleeve 108 within the guide block 106, so that the guide sleeve108 can be inserted into the guide sleeve cavity and the guide sleeve108 can extend through at least a portion of the guide block 106. Thek-wire lumen 110 through the guide sleeve, and the k-wire lumen 110through the guide block can be aligned so that the intended k-wiretrajectory passes through both the guide sleeve 108 and the guide block.Alternately, the guide sleeve 108 can extend all the way through theguide block, and the k-wire lumen 110 can extend through the guidesleeve 108. The guide block 106 can be inserted securely into the windowof the guide frame, and when the guide block 106 is secured in the guideframe, the intended trajectory of the k-wire can pass through the k-wirelumen 110, and the entry point 602 and exit point 604 of scaphoid bone502. In various embodiments, the guide block can be printed with theguide sleeve 108 as a unitary part of the guide block 106, and thek-wire lumen 110 will be aligned along the intended k-wire trajectory.In another embodiment, the guide block can be free of a guide sleeve,and the k-wire lumen will extend through the guide block 106 from thebottom of the guide block to the top surface 1106 of the guide block106. In another embodiment, the guide sleeve cavity can extend throughthe guide block from the top surface 1106 to the bottom of the guideblock, and the k-wire lumen can pass through the guide sleeve. Inanother embodiment, the guide sleeve cavity can extend partially throughthe guide block, and the k-wire lumen can extend through the guidesleeve and through the guide block.

Because the locations and geometries of the guide block 106, which caninclude a guide sleeve 108, plus the entry point 602 and exit point 604of the scaphoid bone 502 are all known in the same 3-dimensional space,the correct insertion length of k-wire can also be known. The maximuminsertion length of k-wire can be known from the 3-dimensionalrecreation so that the k-wire does not extend beyond the exit point 604to a distance that would cause injury to nearby bones, such as theradius. This maximum insertion length of k-wire can be the distance fromthe exit point 604 to the top of the guide block 106, which can be thetop of the guide sleeve 108. The maximum insertion length can then bemeasured and marked on the k-wire prior to insertion of the k-wire intothe lumen(s) and into the scaphoid. When the k-wire has been inserted tothe maximum depth, the mark will be at the top of the guide block 106,which can be the top of the guide sleeve 108.

FIG. 12A shows a bottom view of a guide block with a guide sleeve,according to an embodiment. The guide block 106 can have a bottomsurface 1202. The guide sleeve cavity 1002 can be seen in FIG. 12extending through the guide block to the bottom surface 1202 of theguide block 106. A guide sleeve 108 with a k-wire lumen 110 can beinserted into the guide sleeve cavity 1002. The bottom surface 1202 isdesigned to be inserted into the window of the support frame so that thebottom surface 1202 is facing the skin of the patient. The k-wire canpass through the guide sleeve 108 that is within the guide sleeve cavity1002, through the skin of the patient, and into the entry point 602.

FIG. 12B shows a bottom view of a guide block with a k-wire lumen,according to an embodiment. The guide block 106 can have a bottomsurface 1202, and can have a k-wire lumen 110 extending through thebottom surface 1202. The guide block can be free of a guide sleeve, sothat the k-wire lumen 110 extends entirely through the guide block 106,or the guide block 106 can have a guide sleeve cavity that extendspartially through the guide block, and can have a k-wire lumen 110 thatextends from the bottom of the guide sleeve cavity to the bottom of theguide block.

In various embodiments of a k-wire guidance system having a k-wire bracethat is a stereotaxic instrument, a 3-dimensional model of a k-wirebrace can include the guide sleeve positioned along the desired k-wiretrajectory. Because the position of bone, the desired trajectory, theguide frame, and k-wire brace can all be known in a fixed space relativeto each other, the correct positioning of the guide sleeve along thek-wire trajectory can be determined in the 3-dimensional model. Thecorrect adjustment of each of the degrees of freedom can then bedetermined based on the modeled position of the guide sleeve. A surgeoncan use the graduated markings on the stereotaxic instrument to adjustthe physical guide sleeve into alignment with the guide sleeve of the3-dimensional model. In various embodiments, the 3-dimensional modelingcan include a numeric output indicating the correct adjustment for eachdegree of freedom. By way of non-limiting example, the output couldindicate that the first degree of freedom should be fixed at 20 mm leftof center, the second degree of freedom should be fixed at 37 degreesback from center, etc. A surgeon can then use the numeric output fromthe 3-dimensional modeling of the scaphoid and desired trajectory toadjust the stereotaxic instrument so that the guide sleeve will bealigned with the desired trajectory.

FIG. 13 shows a perspective view of a guide block held within a supportframe, according to an embodiment. Although the k-wire brace is shownand described as a guide block in FIGS. 13-17, it should be clear thatin various embodiments the k-wire brace could be a stereotaxicinstrument. The outer block walls 1102 can be in contact with the innersidewall surfaces of the support frame 104, so that at least a portionof the frustum portion 1104 of the guide block 106 is held securelywithin the block holder 210 of the support frame 104.

FIG. 14 shows a perspective view of a patient's wrist with a windowcasted in place, and a support block with a sleeve, according to anembodiment. A surgeon or other medical provider can place the supportframe 104 against the hand and wrist of the patient, and the medicalprovider can cast the support frame 104 securely in place relative tothe hand and wrist. A 3-dimensional CT scan can then be taken, and thescaphoid bone can be isolated in the known 3-dimensional space so thatthe physician or other medical provider can determine an entry point andexit point for a k-wire. An intended trajectory for the k-wire can beplotted between the entry point and the exit point in the known3-dimensional space. The reference points on the support frame can belocated so that the location of the window of the support frame can beknown in the same 3-dimensional space. A guide block model can bedesigned that will fit securely within the window, and the guide blockmodel can have a k-wire lumen and/or guide sleeve cavity thataccommodates the intended k-wire trajectory. A physical guide block 106can be manufactured that has a k-wire lumen and/or guide sleeve cavityfor a guide sleeve that accommodates the k-wire trajectory when theguide block 106 is fit securely in the window. The guide block 106 asshown in FIG. 14 can be manufactured with a guide sleeve cavity 1102, aguide sleeve 108, and a k-wire lumen 110. The guide block 106 is readyto be inserted into the window 202.

FIG. 15 shows a perspective view of a patient's wrist with a windowembedded in place in the cast, and a support block with a sleeve held inplace within the window, according to an embodiment. As shown in FIG.15, the guide block 106 has been inserted into place within the windowof the support frame 104. The k-wire lumen 110, and the entry point andexit point on the scaphoid bone of the patient are now aligned along theintended k-wire trajectory.

FIG. 16 shows a perspective view of a k-wire being inserted through aguide sleeve and into the scaphoid bone, according to an embodiment. Aphysician or other medical provider can insert a k-wire 1602 through thek-wire lumen, and the k-wire lumen will maintain the k-wire in theintended k-wire trajectory through the entry point and the exit point ofthe scaphoid. Because the locations and geometries of the guide block106, the top of the guide sleeve 108, and the exit point of the scaphoidbone are all known in the same 3-dimensional space, the correctinsertion length of k-wire can be known to the surgeon or other medicalprovider before the k-wire is inserted. Before the k-wire is inserted,the physician or other medical provider can determine from the3-dimensional recreation how many millimeters of k-wire should beinserted through the top of the guide sleeve to reach the ideal depththrough the scaphoid bone without extending through the scaphoid bone toa distance that may cause damage to nearby bones. The ideal depth line1604 can be measured and marked on the k-wire 1602, so that the surgeonor other medical provider will know that the ideal depth has beenreached when the k-wire has been inserted until the depth line 1604reaches the top of the guide sleeve. In embodiments that are free of aguide sleeve, the measurement can be taken from the place where theguide block lumen meets the top of the guide block.

FIG. 17 shows a perspective view of a patent's casted wrist with aninserted k-wire extending through the guide block and guide sleeve,according to an embodiment. The k-wire 1602 has been inserted along theintended k-wire trajectory through the sleeve lumen, the guide blocklumen, and the scaphoid, until the depth line 1604 has reached the topof the guide sleeve 108. The k-wire has been properly installed alongthe intended trajectory, and only one hole has been drilled through thescaphoid.

FIG. 18 shows a perspective view of a patient's casted wrist with theguide block removed and with the inserted k-wire extending from thepalm, according to an embodiment. After the k-wire 1602 has beenproperly inserted along the intended trajectory, the guide block can beremoved from the support frame 104, and the guide block can be slidalong the k-wire 1602 until the guide block is free from the k-wire.

FIGS. 19 and 20 show perspective views from a CT showing a k-wire thathas been properly installed through a scaphoid bone. After the k-wire1602 has been installed, a medical provider can take at least one newx-ray, CT, or other images showing the trajectory of the k-wire 1602.These images can allow the surgeon or other medical provider to verifythat the k-wire has been properly guided along the desired trajectorythrough the bone 502. As shown in FIG. 20, the k-wire 1602 can extendsafely beyond the exit point of the scaphoid bone 502 if the k-wire doesnot impact other nearby bones.

FIG. 21 shows a perspective view of a patient's casted wrist with aninserted k-wire that has been cut for use as a guide for a percutaneousscrew, according to an embodiment. The k-wire 1602 can be cut to alength that is convenient to be used as a guide for the installation ofa percutaneous screw. Because the k-wire 1602 has been installed alongthe desired trajectory, a surgeon or other medical provider can proceedto install the percutaneous screw using the k-wire as a guide, so thatthe percutaneous screw will also follow the desired trajectory throughthe bone. Depending on the preference of the surgeon, the percutaneousscrew can be installed before or after the cast is removed.

As used herein the directional terms, such as, but not limited to, “up”and “down”, “upward” and “downward”, “rear”, “rearward” and “forward”,“top” and “bottom”, “inside” and “outer”, “front” and “back”, “inner”and “outer”, “interior” and “exterior”, “downward” and “upward”,“horizontal” and “vertical” should be taken as relative conventions andnot as absolute orientations with respect to a fixed coordinate system,such as the acting direction of gravity. Additionally, where the term“substantially” or “approximately” is employed with respect to a givenmeasurement, value or characteristic, it refers to a quantity that iswithin a normal operating range to achieve desired results, but thatincludes some variability due to inherent inaccuracy and error withinthe allowed tolerances (e.g. 1-2%) of the system.

It should be clear to one of ordinary skill that the foregoing providesa system and method for fixing a scaphoid or other fractured bone byinserting a k-wire through the fractured bone. The k-wire can beinserted through a guide block that can be held in place by a blockholder that can be casted securely in place relative to the fracturedbone. The guide block can be custom designed for each patient, and canbe printed using a three-dimensional printer. The guide block that issecured in place relative to the fractured bone can ensure that thek-wire is inserted along a correct trajectory, so that the k-wire onlyneeds to be inserted one time, thereby minimizing potential errors andcomplications.

The foregoing has been a detailed description of illustrativeembodiments of the invention. Various modifications and additions can bemade without departing from the spirit and scope of this invention.Features of each of the various embodiments described above may becombined with features of other described embodiments as appropriate inorder to provide a multiplicity of feature combinations in associatednew embodiments. Furthermore, while the foregoing describes a number ofseparate embodiments of the apparatus and method of the presentinvention, what has been described herein is merely illustrative of theapplication of the principles of the present invention. For example,support frames can be various shapes and sizes, so that the presentmethod can be applied to various other fractured bones that can benefitfrom correct placement of a k-wire. Likewise, a guide block can becustom designed for the installation of a k-wire through various bonesthat can benefit from correct installation of a k-wire. Also, as usedherein, various directional and orientational terms (and grammaticalvariations thereof) such as “vertical”, “horizontal”, “up”, “down”,“bottom”, “top”, “side”, “front”, “rear”, “left”, “right”, “forward”,“rearward”, and the like, are used only as relative conventions and notas absolute orientations with respect to a fixed coordinate system, suchas the acting direction of gravity. Additionally, where the term“substantially” or “approximately” is employed with respect to a givenmeasurement, value or characteristic, it refers to a quantity that iswithin a normal operating range to achieve desired results, but thatincludes some variability due to inherent inaccuracy and error withinthe allowed tolerances (e.g. 1-2%) of the system. Accordingly, thisdescription is meant to be taken only by way of example, and not tootherwise limit the scope of this invention.

What is claimed is:
 1. A guidance system comprising: a cast; a guideblock, the guide block having a central lumen through the guide blockalong a predetermined k-wire trajectory; and a support frame, thesupport frame comprising at least one sidewall configured for holdingthe guide block, wherein the support frame is adapted to be heldsecurely relative to a fractured bone of a patient by the cast, and theguide block is designed to fit within the support frame, so that thecentral lumen is aligned along the predetermined k-wire trajectory. 2.The guidance system of claim 1, wherein the support frame furthercomprises a brim.
 3. The guidance system of claim 2, wherein the atleast one sidewall defines a block chamber, the block chamber defining afirst area near the brim that is smaller than a second area distant fromthe brim.
 4. The guidance system of claim 1, further comprising a guidesleeve, the guide sleeve having a sleeve lumen that is aligned along thepredetermined k-wire trajectory.
 5. The guidance system of claim 1,wherein the guide block further comprises a frustum.
 6. The guidancesystem of claim 1, wherein the k-wire trajectory defines a predeterminedpath adapted to pass through the fractured bone.
 7. A guidance systemcomprising: a cast configured to immobilize a portion of a patient; aguide block defining a central lumen that defines a predetermined k-wiretrajectory; and a support frame secured relative to the portion of thepatient by the cast, the support frame comprising at least one sidewallconfigured for receiving the guide block such that the central lumen isaligned along the predetermined k-wire trajectory.
 8. The guidancesystem of claim 7, wherein the predetermined k-wire trajectory isdetermined based upon an image of the portion of the patient.
 9. Theguidance system of claim 8, wherein the image is captured after the castand support frame are secured relative to the portion of the patient.10. The guidance system of claim 8, wherein the image of the portion ofthe patient is acquired by a CT scan and is used to generate a 3Dreconstruction of the portion of the patient.
 11. The guidance system ofclaim 8, wherein the predetermined k-wire trajectory defines at leastone of an entry point or an exit point relative to the 3Dreconstruction.
 12. The guidance system of claim 7, wherein the portionof the patient comprises a hand or a wrist.